Can you name a British composer active in the 1910s and 1920s whose music approaches Stravinsky's Rite of Spring for novelty? A genius whose music is brilliantly inventive and yet distinctive? Whose pieces stand alongside the boldest French and German music of that era, and who, by his 20th birthday, had met both Gustav Mahler and Richard Strauss and was profoundly influenced by both? My guess is that even the most knowledgeable among you would find it hard to name such a person. Yet this composer did exist, and I hope I can restore him to his rightful place at the heart of British repertory.

My first contact with the music of John Foulds came a decade ago. I had just been appointed principal conductor of the CBSO, and my eyes and ears were wide open to all things English. Just before my move to Birmingham, I was in Helsinki talking to a German journalist. Our conversation turned to English music and he raved about one name in particular, John Foulds, and showed me his barely readable, minuscule and battered copy of the score of Three Mantras.

This long neglected work represents not only the pinnacle of Foulds's output, but, I believe, the peak of all British orchestral music written between the two world wars. I was struck by its elemental, visceral power, the other-worldly serenity of the second movement, Mantra of Bliss, and the virtuosic self-assurance with which the composer marshalled a multitude of ideas from Hindu mysticism, to rhythmic ecstacy, into a convincing whole. I immediately wanted to know more about the man who wrote this music yet who seemed to have passed completely into oblivion.

Born in Manchester in 1880, John Foulds put down his musical roots in soil nourished by the new sense of direction that British music found in the final years of the 19th century. He left home at 13, making his living playing cello in theatres and cabarets and, in 1900, he gained a position in the Hallé Orchestra. The Hallé, under conductor Hans Richter, was then enjoying one of the most interesting phases in its existence, with strong links through Richter to the mainstream European tradition represented by Brahms and Bruckner. Richter encouraged Fould's own efforts at composition, and the young musician's first mature works - such as the elaborately Straussian tone-poem Mirage, and Apotheosis, an elegy for violin and orchestra - indeed reveal French and German influences, but there was much more to come.

Meeting his future wife, the ethnomusicologist Maud McCarthy, and joining the theosophical movement generated a vivid interest in eastern, particularly Indian and Arabic, music, as well as in recreating the ancient musical cultures of the Greeks and Celts. Those influences can be seen first in Foulds's songs and piano music, and are evident too in his works of the early 1920s, when they became an integral part of his musical language.

In terms of public recognition, the early 1920s were the peak of Foulds's career. His World Requiem (1919-21), a plea for the unity of mankind, was performed three years running on Remembrance night at the Royal Albert Hall, but has since been neglected. There has yet to be a modern performance, so it's only possible to judge this vast piece from the score. In it Foulds shows his mastery, undoubtedly acquired from his experience in the theatre, of using the performing space and a wide range of solo, choral, and orchestral forces to achieve maximum effect. Despite public acclaim, critical response was hostile, reflecting the direction British culture was taking after the first world war, when anything too visionary or innovative was viewed with suspicion. The failure of the requiem to establish itself in the choral repertory proved a crucial setback in Foulds's composing career.

An even more ambitious yet incomplete project was the opera Avatara - the title refers to various human or supernatural incarnations of the Hindu god Vishnu - on which Foulds worked for more than a decade. He finished 420 pages of orchestral full score but, by 1930, perhaps daunted by the sheer scale of the work and by the prospect of presenting his masterpiece to a public he suspected would be indifferent to it, he had destroyed all but 80 of those pages. Those that remained became the Three Mantras, a work that demonstrates all that is best about Foulds's music - its ability to take complete possession of listeners and lead them through unexplored concepts of time and place.

Unlike many of his composing peers his interest in Indian music wasn't cosmetic: he didn't simply glue the exotic elements on top of his own music, but actually allowed them to change his own musical style. Foulds went deeply into the theoretical details of the different scales, modes and rhythmic idioms of the vast musical heritage of the subcontinent. It could even be claimed that he did for Indian music something similar to Bartok's folk-song research in the Balkans, and, like Bartok, he made the results of his theoretical efforts an organic constituent of his own musical style.

By the late 1920s the public indifference to Foulds's musical efforts was taking its toll, and to earn a living he increasingly turned towards writing theatre music and occasional pieces. In 1927 he moved to Paris where the cultural climate was freer. There he got to know the members of Les Six, and also met Stravinsky and Varèse, and he produced another masterpiece, the Dynamic Triptych. This splendid, virtuoso piano concerto's first movement, Dynamic Mode, is probably the most dissonant piece Foulds was to write, while its second movement, Dynamic Timbre, contains a wonderfully romantic tune that could have been composed by a hybrid Ravel and Rachmaninov.

Returning to Britain in 1930, there were more masterpieces to come, such as the Quartetto Intimo, a strong, tight and dramatic string quartet finished in 1932. But still restless, Foulds embarked on yet another trip, to India, where he was to remain until the end of his life. In 1937 he became director of the European Music Department at All-India Radio, where, as well as giving weekly piano recitals, he worked on a new style of "Indo-European" musical fusion, for which he created an "Indo-European Orchestra". There was a plan to write a east-west symphony, but all this incredibly interesting fermentation was cut short by cholera. Foulds contracted the disease and died - "in exile", as he described it - in Calcutta in 1939.

Since the CBSO and I have been rediscovering and performing Foulds in Birmingham over the past three years, the results have been hugely encouraging. Audiences have been enthusiastic, and it has been hard to understand how history can have been so wrong in its judgment of his music. It also raises the question of how many more composers of Foulds's quality have disappeared without trace. There is still much more to be done, and I want to take this opportunity to make a request. The performing material of Foulds's concert opera The Vision of Dante, composed in the 1900s, is awaiting restoration at the British Library. Who will have the generosity and courage to take on such a project?

I called Foulds a genius earlier. Many would argue against this. For me, though, Foulds was a serious composer, one with unusually wide interests and understanding of the world, who fully deserves his long overdue revival.

·Sakari Oramo conducts John Foulds's April-England at Symphony Hall, Birmingham, tomorrow. Box office: 0121-780 3333. His second disc of Foulds's music with the City of Birmingham Symphony Orchestra is released this month on Warner Classics.